An unmanned high-altitude spy plane has made aviation history by completing the first non-stop, robotic flight across the Pacific from California to Australia, US defence officials said on Tuesday.

The Global Hawk, a jet-powered aircraft, flew from Edwards Air Force Base in California and landed late on Monday at the Royal Australian Air Force base at Edinburgh, in South Australia.

The 13,840km (8,600 mile) flight, at an altitude of almost
20km (12.5 miles), took 22 hours and set a world record for the furthest a robotic aircraft has flown between two points.

The plane can fly non-stop for 36 hours

The Global Hawk flies along a pre-programmed flight path, but a pilot monitors the aircraft during its flight via a sensor suite which provides infra-red and visual images.

"The aircraft essentially flies itself, right from
take-off, right through to landing, and even taxiing off the runway," said Rod Smith, the Australian Global Hawk manager.

Huge wingspan

The awkward-looking plane has a bulbous nose that hides an antenna 1.22 metres (4 feet) in diameter.

On take-off, its mammoth wings - longer than a Boeing 737's - droop under 15,000 pounds of fuel that accounts for 60% of the aircraft's weight.

It can fly non-stop for 36 hours and is designed to search up to 137,000 sq km (52,895 square miles) in 24 hours, criss-crossing a target to acquire radar, infra-red and black-and-white images before returning home.

After taking off from Edwards Air Force Base, the spy plane flew at 65,000 feet - well above other air traffic and the bad weather that plagues the Pacific.

Military exercises

Having landed in Australia, it will now take part in
combined US and Australian military exercises over the following six weeks.

It will fly about 12 maritime surveillance and reconnaissance missions around Australia's remote coastline.

Each Global Hawk will cost between $10m and $20m and the first of 63 production models is expected to be delivered to the US Air Force in 2003.

Australia is assessing the aircraft's capabilities and might also buy it.

Combat power

"Emerging systems such as the Global Hawk offer Australia great potential for surveillance, reconnaissance and ultimately the delivery of combat power," said Brendan Nelson, parliamentary secretary to the Australian defence minister.

Mr Nelson said the Global Hawk could be used in combat to "detect, classify and monitor" targets as they approached the Australian coast.

The US Air Force has named the plane "Southern Cross II" in honour of the first aircraft to fly from the United States to Australia.

The original Southern Cross was a three-engined Fokker that departed from Oakland, California. Its crew completed the journey to Australia in several legs in 1928.